Could you clarify: Do you mean that your first attempt at starting the vehicle always fails? so you turn the key for 5-6 seconds, then wait, then try a second time and it starts?
If so, many people have this problem.
You should start by checking your fuel pressure at the fuel rail, Borrow a pressure gauge and connect it to the shrader valve on the fuel rail, it should be very easy to do. It should be above 30 psi while at idle. Turn the engine off, it should be above 10 psi after 30 minutes. Come back and tell us the results.